In a machine tool on which an NC unit (numerical control unit) is mounted, a work is machined into a desired product shape by executing the NC program. To create the NC creation program for creating the NC machining program, recently, an automatic programming technique using a microcomputer referred to as an automatic programming device has been frequently used.
The early automatic programming devices were not connected to the CAD data, and hence, it was necessary to perform programming, while watching the machining shape in a drawing or the like. However, recently, some techniques relating to the automatic programming device that creates the NC machining program by the CAD data have been proposed.
For example, in (Japanese Patent Application Laid-Open No. 2002-189510), feature data of a machined product is extracted from the CAD data to set a machining process and a machining area for each machining process, material data and a machining model for each machining process are created, the created machining process data and machining model data are stored, tool path data is created based on the machining process data, material data, machining model data, tool data, and cutting condition data, to create virtual work shape data after completing the respective processes, as well as creating fabrication information based on the created process data, material data, tool path data, and virtual work shape data.
In (Japanese Patent Application Laid-Open No. 2002-268718), when a machining path for machining a workpiece based on a three-dimensional CAD data of a part is created, machining information for all portions to be machined in a shape indicated by the three-dimensional CAD data is extracted, the extracted machining information is edited to determine a machining process, and the machining path is created based on the determined machining process.
In such type of automatic programming device, a product model is arranged in a work model, and machining data has to be created as a difference between the product model and the work model. At this time, it is desired that the product model can be automatically arranged easily in the work model.
In (Japanese Patent Application Laid-Open No. 2001-117616), it is disclosed that an object solid model (product model) and a workpiece solid model (work model) are overlapped on each other and combined, to obtain a synthesis model indicating a capacity portion of a workpiece, which has to be removed in order to form the object. Specifically, a human user selects at least one of topological feature types, selects a surface of the synthesis model, associates a related one portion of the model having the selected surface with the selected topological feature type, defines the portion having the selected surface as a machining feature topologically equivalent to the selected topological feature type, and divides the capacity portion to be removed into many machining features.
In the conventional art described in Japanese Patent Application Laid-Open No. 2001-117616, however, how to overlap the object solid model (product model) and the workpiece solid model (work model) is not particularly described.
The present invention has been achieved in order to solve the above problems, and it is therefore an object of the invention to provide an automatic programming method and device that can position the product model on the work model with quite simple operation, and can achieve efficient programming operations.